Rick the problem isn't the sprinkler it's the valve. Water can't get to that sprinkler unless it gets past that valve.

Find the valve, take the bonnet off, inspect the diaphragm. There's a good chance there's debris stuck in the seat of the diaphragm. You may need to replace it.
Also look at the seat itself and see if it's pitted. Sometimes you can sand that out with some fine grit sand paper.